lightemup67

Well I screwed up my first brake fluid flush:

I bought the motive bleeder, the nice brake fluid, and went to work this weekend. I followed the directions and was all good until the right front wheel. I checked that I had fluid left in the reservoir, but either saw a shadow instead of fluid line, or it drained extremely fast.

I ran the reservoir dry, and sucked air through the system. Extremely annoyed at myself, I started from scratch: filled the reservoir, pressurized the system, and started back at wheel 1 (right rear). This time I completed all four wheels and refilled the reservoir each time.

However, the brake pedal was still very mushy. SO I decided to get my wife to help me and manually bled all four corners again with her forcing the fluid through with the up/down pedal method. Yet this didn't help and I got no air bubbles out of any of the 8 bleeder valves.

Finally, (and this is the worst part) after reading a few forums, I fired up my icarscan to see if I could make the computer do the ABS/ pump operation. I went to the brake bleed screen, followed the directions, heard the pump operate, and then got a bunch of codes: ABS, PSM, parking brake, and something called "Roll over mode".

I've bled hundreds of brake systems, and it is always straight forward. I feel like a complete bum haha.

The car stops okay (just very mushy). So my approach will be to start all over again, but I'm not sure if I damaged something with the icarscan. Should I just try to clear all those codes once I'm done re-doing the flush/bleed?

Any advice welcome!

dbv1

Why not just fill the Motive bleeder with brake fluid and pressurize it? It’s impossible to introduce air into the system as long as the bleeder has any fluid and is pressurized.

lightemup67

Honestly, I tried that but the Motive bleeder seemed to be pushing air into the reservoir as well. I filled it with 1.5 liters of fluid, started pumping, and all the air in the motive line was being forced into the reservoir first (before the liquid). Is there some way to bleed the system to ensure that doesn't happen?

Also, update on the error lights... stupid user error. Accidentally left it in brake service mode. Once I exited, it was all cleared up.

I'd love to figure out how to use the Motive system without forcing air into the reservoir, but all the how-to videos didn't mention anything about bleeding the line.

deilenberger

The air is already there.;... that truck left the depot in his intro post.

OP - this is the iCarScan X431 (orange dongle)? I haven't looked carefully at the bleed option for the Cayenne since I've had that done professionally, but on my boxster with the iCarScan there was an "Activate ABS/PSM" - which I used for bleeding. My mechanic friend who was working the calipers was impressed that after we did this WHILE he was bleeding the right/rear cylinder air came through. And now the pedal is much firmer. There must have been air trapped in the ABS pump. I suspect that's your problem, and it might be useful to have two people on the project - one to trigger the ABS motor (I only ran it for a minute or so..) and the other person at the RR bleed nipple. Apparently once you get air into the pump - it's not coming out unless you power flush it.

Once that's done clear the codes - they won't come back.

lightemup67

Ah thanks, that sounds like a good idea. I suspect that's my issue as well. Will report back when after I try that.

garrett376

Just re-bleed it and you'll get it back to normal operation. The factory manual specifies to use the brake pedal with the pressure bleeder which helps speed up the process, too. And I always use a Motive bleeder dry - unless you're a workshop doing bleeds constantly, the old fluid in there must get cleaned out completely, and cleaning that thing completely is a messy task that's easily avoided. If I were in your situation where it's possible you introduced air into the PSM/ABS, I'd re-bleed it, then do the PSM/ABS bleed function. In the future unless you replace the PSM/ABS pump, you don't need to actuate anything when bleeding/flushing.

dbv1

I know, just trying to make his life easier next time around.

It’ll look like that, the line going to the reservoir will look like it’s full of air with some fluid but that’s normal. Just watch the reservoir, it’ll never go down in level as you’re bleeding. Either that or your bleeder is broken.

Spyerx

My bleeder bottle is 500ml. I draw lines on it. So each line is 125ml. I like to pull just under 200 on outside then 50 or so on inside. Check reservoir every 125 or so better safe than sorry.

was bleeding driver rear on 991 this weekend and about 125ml in a bunch of air comes out. Thought reservoir was dry but not. Just air in line.... pulled a lot more to make sure. Always like to have 2l of fluid in case of screw ups. Btdt

X-TNSIV

I recently went through the same process with using my motive for the first time.

I ran 2L of brake fluid before I did enough research to find out I was drawing air in through the bleeder valve.

I did fill the pressure bleeder with fluid and pumped it into the MC that way.

https://rennlist.com/forums/cayenne-...placement.html

deilenberger

The point I tried to make in my posting above (but apparently was unsuccessful) was - you will never get air out of the PSM/ABS modulator unless you're activating it when you are flushing fluid through the system. AND you have to activate it for each channel (there are 4 - one for each wheel) while bleeding that channel.

I can't think how to make that clearer - but that's how it is..

dhc905

Curious what "roll over mode" is? If you flip the Pig and plug in your scanner to see why everything is upside down?

lightemup67

yes exactly, and the doors turn into gull-wings to roll you back over.

It had something to do with testing brakes while you were rolling? Entered that screen by mistake and it didn't want to exit. I find the icarscan a little scary in that regard. My app is pretty finicky.

docwyte

You've probably pushed air into the ABS system. Unless you have a way to cycle the ABS while bleeding its time to take it into a shop that can do that for you. I've used a Motive bleeder with fluid in it for over 15 years without an issue but you have to make sure you don't run it out of fluid...

lightemup67

Agreed with the ABS. Can anyone help me with the icarscan directions/ approach? I tried the brake bleed procedure again last night and its just hard to follow and finicky.

There is also the PSM test screen which I figure is the same thing. It tests the PSM (which also is the ABS right?), at each wheel while you spin the wheel to ensure all four corners are operating. If I use that procedure on icarscan, but bleed the valves while the PSM is firing, I should be letting any air out right?

At this point its the principle of the matter haha, taking it to Porsche is my last resort.

lightemup67

To close the loop on this.... I was able to clear the air out of the pump with the icarscan using a different module. Instead of the brake bleed (which was super confusing and times out in 2 minutes if you don't move through the steps), I used the PSM test screen.

In iscarscan app, find the Select service>PSM and then it was something like pump test or actuation test. To test PSM you're supposed to have all 4 wheels up and in neutral so you can spin the wheel, fire the pump, and watch if the wheel stops. However, to use it for the brakes, you can hook up your motive bleeder, open the valve at the wheel it tells you, and start the test. You see a bunch of fluid push out while it fires the pump for about 1-2 seconds. Then close the bleeder valve. It allows you two tests on each wheel (which is perfect for the inner and outer valves) before moving to the next wheel.

Brakes feel firm now. Wish they were firmer but I think that's a bit of the nature of this SUV.

Hope this helps someone in the future.